Longitudinal changes in clusters of cancer patients over an 18-month period

Cross-sectional studies in cancer have revealed the presence of clusters of symptoms (e.g., gastrointestinal, emotional) and of patients (e.g., low or high levels of symptoms), but not much is known about their longitudinal evolution. In addition, their relationships with medical factors (e.g., cancer sites, treatments) and possible consequences (e.g., functioning) have yet to be established. This prospective study assessed the presence of clusters of patients in 828 participants scheduled to undergo surgery for cancer.

The patients completed the Hospital Anxiety and Depression Scale, the Insomnia Severity Index, the Multidimensional Fatigue Inventory, the EORTC Quality-of-Life-Questionnaire-C30, and a physical symptoms questionnaire at baseline and 2, 6, 10, 14, and 18 months later.

Cluster analyses identified between five and eight clusters of patients depending on the time point. The "Low Symptoms" cluster was the most common (24.8 to 35.0% of the sample), whereas one with predominant nausea and vomiting symptoms was among the least common (1.6 to 3.5%). Significant differences were found between cancer sites, treatment regimens, quality of life, and functioning scores. Prostate cancer patients and those treated by surgery only were overrepresented in the "Low" cluster, whereas breast cancer patients were more likely to fall into the "Moderate - Night Sweats" cluster. Clusters with more severe psychological symptoms were associated with lower functioning and quality of life.

This study revealed distinct clusters of patients that varied in number during cancer treatments. Findings also identified some clusters associated with lower quality of life and functioning, which should receive more clinical attention.